Headlight lens



Aug; 14, 1934. Q J BURGER 1,969,714

HEADLIGHT LENS Filed Oct; 30. 1955 INVENTOR.

BY I M6 4. 0" .w

ATTORNEYS.

' ARLHJ-B RGER.

Patented Aug. 14, 1934 UNITED STATES PATENT OFFICE 1 Claim.

This invention relates to automobile headlights and has for its object a specially devised, though simple and cheap, lens which will produce a beam free from objectionable glare to B motorists coming in the opposite direction yet yield a powerful and safe driving light to the driver of the car equipped therewith.

My invention is illustrated in the drawing accompanying this application and in which Fig. 1 is a perspective view of a vehicle headlight equipped with my improved lens.

Fig. 2 is an enlarged vertical central section of the lamp taken through the line 22 of Fig. 1.

Fig. 3 is an enlarged cross section of the lens and clamping rim of the lamp taken along the line 3-3 of Fig. 1

My improved lens glass is adapted to replace the glass in front of most vehicle headlights in use and is here shown applied to a conventional 20 headlight having a parabolic reflector 1, a source of light such as an incandescent filament 2 of bulb 3, an outer clamping ring or rim 4 cooperating with an inner fixed flange 5 to hold the lens 6 in place.

The lens 6 is preferably of white lens glass as generally used on headlights and it comprises a flat disk portion 6 with an oblong centrally disposed recess 7 in its front face. This recess is about 2/3rds the height or diameter of the glass 30 and a little more than half as wide as high, the best effect generally requiring a width about 3/5ths that of the height. The recess has flat side walls 8 extending inwardly at right angles to the plane of the glass, and a bottom wall 9 inwardly curved, as shown in Fig. 2 preferably on a simple circular arc struck from a point on the central horizontal axis X of the lamp. The inwardly curved wall is generally displaced about one-half inch at its greatest depth from the sur- 40 face of the flat portion and is of clear glass preferably of even thickness.

The remainder of the lens, flat portion 6, and both side walls 8 of the recess are frosted (preferably on the inner surface) as by grinding or otherwise to interrupt the rays and prevent the issuance of a clear beam of light except through the clear curved bottom wall 9 of the recess.

The width of the recess varies somewhat with the size of the electric globe and focus of the re- 5 flector used for the light, and the width generally found to give best results is one about equal to the diameter of the globe, though recess widths of about three inches give very good results with the average automobile headlight.

Lamps thus constructed have been found to give a well-lighted foreground on the highway while throwing out a powerful central beam without glare to approaching vehicles, and the effective distance handled by the central beam may be varied by focusing the light bulb 3 back and forth in the parabolic reflector 1.

The exact optical reasons for the unlooked for performance of this lens Icannot state, but it has largely to do with the inward cylindrical curving of the bottom clear wall 9 of the recess as the presentation of the convex rear surface of this clear portion to the source of light seems to turn back rays seeking to emerge at injurious angles for re-reflection at more appropriate angles through the more central portions, and the cutting of a window opening entirely through the frosted lens instead of using the inwardly curved clear wall will not yield the desired result.

Having thus described my new headlight lens, what I claim is:

In combination with a vehicle headlight having a light source and a reflector of substantially parabolic type extending from in back of the light source to a point forward of the light source, a disk of glass of a non-transparent light-diffusing character closing the forward end of the reflector provided with a vertically arranged elongated depression in its face having a bottom curved lengthwise only to substantially cylindrical form with its convex side presented to said light source and being of substantially even thickness of glass, the depression having side walls extending substantially at right angles from the plane of the disk rearwardly to the curved bottom and the curved bottom only of the depression being of clear glass.

CARL H. J. BURGER. 

